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OAR Box 1111 

Prepped by Ryan Dugan 

Document Number: 

-W) ll-A-8 

Docket Number: 

A-83-22 

Printed 4/15/2008 1:25:18 PM Sheet 117 of 118 
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PEI ASSOCIATES 
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SEASONAL VARIATIONS IN THE AMOUNT OF 

TIME CHILDREN SPEND INDOORS, 

OUTDOORS, AND IN MOTOR VEHICLES 

by 

Anne Pope 

PEI Associates, Inc. 

505 South Duke Street, Suite 503 

Durham, North Carolina 27701-3196 

Contract No. 68-02-4309 

Work Assignment No. 9 

PN 3659-9 

Richard B. Atherton, Project Officer 

Jeff Cohen, Work Assignment Manager 

STRATEGIES AND AIR STANDARDS DIVISION 

U.S. ENVIRONMENTAL PROTECTION AGENCY 

RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711 

January 1986 
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DISCLAIMER 

This report was prepared by PEI Associates, Inc., Cincinnati, Ohio, 

under Contract No. 68-02-4309, Work Assignment No. 9. It has been reviewed 

by the Strategies and Air Standards Division of the Office of Air Quality 

Planning and Standards, U.S. Environmental Protection Agency and approved for 

publication. Approval does not signify that the contents necessarily reflect 

the views and policies of the U.S. Environmental Protection Agency. Mention 

of trade names or commercial products is not intended to constitute endorsement or recommendation for use. 

n 
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CONTENTS 

Page 

Figures iv 

Tables iv 

Acknowledgment v 

1. Introduction . ....... . 1 

2. Methodology 2 

Formation of demographic groups 2 

Estimation of activity patterns 4 

3.' Results 6 

4. Comparison of the Estimates of PEI and EPA 8 

References 10 

m 
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FIGURES 

Number 

1 

2 

Example of Estimate of Time Spent in Microenvironments. . 

Example of Breakdown of Time Spent in Microenvironments 

According to Activity . . . 

Page 

4 

TABLES 

Number 

1 

2 

3 

Page 

Demographic Groups of Children. . 3 

Summary of Activity Patterns of Children 7 

Average Daily Time Children Spend Indoors, Outdoors, and 

in Motor Vehicles 9 

iv 
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ACKNOWLEDGMENT 

This report was prepared for the U.S. Environmental Protection Agency by 

PEI Associates, Inc., Cincinnati, Ohio. Mr. Jeff Cohen was the EPA Work 

Assignment Manager. Mr. David Dunbar served as the Project Director; 

Mr. Ted Johnson was the Project Manager. The principal author was Ms. Anne 

Pope. The author would like to thank Mr. Jeff Cohen for his guidance and 

direction on this Work Assignment. 
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SECTION 1 

INTRODUCTION 

The U.S. Environmental Protection Agency (EPA) is currently assessing the 

lead exposure of children in seven age groups (0 to 0.99 year, 1.00 to 1.99 

years, 2.00 to 2.99 years, 3.00 to 3.99 years, 4.00 to 4.99 years, 5.00 to 

5.99 years, and 6.00 to 6.99 years). Based on the motor, mental, and social 

development and the weekday location of children, the seven EPA age groups 

have been aggregated into four age groups (0 to 0.99 year, 1.00 to 1.99 years, 

2.00 to 4.99 years, and 5.00 to 6.99 years) to estimate the time that children 

spend in three microenvironments: outdoors, indoors, and in motor vehicles. 

Under Work Assignment No. 9, Contract No. 68-02-4309, PEI Associates, Inc. 

(PEI) has developed estimates of these microenvironmental time allocations 

from activity patterns data previously compiled for an analysis of 

population exposure to ozone. This report describes the methodology 

employed by PEI in developing the time allocations, summarizes the time 

allocations according to.demographic groups and climatic season of the 

year, and compares the results developed by PEI to time allocations previously developed, by EPA. 
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SECTION 2 

METHODOLOGY 

Because of time and resource constraints, PEI used previously developed 

activity patterns of children exposed to ozone to estimate daily time allocations of children who are potentially exposed to lead in three microenvironments. The microenvironmental time data contained in the ozone activity pattern forms were analyzed and reduced to calculate the microenvironmental time 

allocations of children exposed to lead. Section 3 presents the estimated 

time allocations of four age groups of children exposed to lead. 

This section describes the methodology PEI used to identify demographic 

age groups and to develop activity patterns for children exposed to ozone. 

The identification of appropriate demographic age groups of children and 

the construction of reasonable activity patterns were based on a detailed 

review of the current literature. In the assessment of the ozone exposure 

of children, PEI most frequently used the following articles to specify the 

demographic groups and to develop activity patterns for the groups: J. P. 

Robinson, How Americans Use Time, 1977; M. D. Koontz and J.P. Robinson, 

Population Activity Patterns St. Louis Study, 1982; D. J. Moschandreas et 

al., Comparison of Indoor and Outdoor Air Quality, 1981; and R. Hart, 

Children's Experience of Place. Other sources are indicated in the text 

where appropriate. 

2.1 FORMATION OF DEMOGRAPHIC GROUPS 

Based on a memorandum prepared by PEI on the development of activity 

patterns for children exposed to ozone, a listing of the demographic groups 

of children is presented in Table 1. Age, census data, and activity data 

were used to classify the population of children into four groups. The 

factors of age, weekday location, and motor, mental, and social development 

served as a basis for the division of children into groups. 
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TABLE 1. DEMOGRAPHIC GROUPS OF 

Demographic qroup 

0 to 0.99 year old 

1 to 1.99 year old 

2 to 4.99 year old 

5 to 6.99 year old 

CHILDREN 

Stage of development 

Baby 

Toddler 

Preschool child 

Kindergarten and school-age 

child 

Because of their similar physical, mental, and social characteristics, 

children 0 to 0.99 years of age are grouped together. Babies spend most of 

their time sleeping. When they are awake, they spend their time eating and 

becoming aware of their immediate surroundings through touching, listening, 

looking, sitting, creeping, active play with objects, and socializing with 

family members. Toddlers 1 to 1.99 years of age exhibit the characteristics 

of walking, perceptual preferences with respect to tastes and colors, 

speech development, classification of objects, imitative play, and solitary 

or parallel play. Because children 0 to 1.99 years of age have difficulty 

tolerating separation from their mothers or mother figures, PEI has assumed 

that, on weekdays, the majority of babies and toddlers stay in the homes of 

their parents or in homes of caretakers with small numbers of children 

(usually less than six) rather than in day-care centers. 

Children 2 to 4.99 years of age usually attend some type of preschool for 

a portion of each weekday. The maturation of preschoolers includes increased 

motor development at gross and fine levels, mental representation of the 

environment, perceptual discrimination and organization, language development, 

ability to accept temporary absences of their mothers, increased socialization 

with other children, and cooperative play. Kindergarten and school-age 

children 5 to 6.99 years of age are classified into a single demographic group 

because they attend school for approximately the same period of time daily. 

Kindergarten and school-age children socialize in peer groups, play games with 

rules, associate primarily with members of their own sex, and represent ideas 

in a coordinated manner. 
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2.2 ESTIMATION OF ACTIVITY PATTERNS 

For each demographic group listed in Table 1, activity patterns for 

ozone exposure were developed for cool and hot weekdays, Saturdays, and 

Sundays. The three microenvironments where activities could occur included 

indoors, outdoors, and in motor vehicles. Ten-minute intervals were used 

to document the elapsed time of each activity during a 24hour period. 

To develop the activity patterns of individual demographic groups, PEI 

reviewed the literature and conducted informal surveys. Initially, 

a rough estimate was made of the amount of tfme spent daily in the three 

microenvironments. This estimate was further refined into different activities performed in the microenvironments. Examples of activities included 

sleeping, eating, traveling, playing, and doing school work. References, 

documentation of activities, and additional factors that might possibly 

alter the data were noted for each activity pattern. Figures 1 and 2 

show examples of the two steps followed in the development of an activity 

pattern for preschoolers on a cool weekday. 

Demographic group: Children, age 2 to 4.99 years 

Day and season: Cool weekday 

Microenvironment Time 

Indoors - residence 

Indoors - school 

Indoors - other 

In motor vehicle 

Outdoors - residence 

Outdoors - school 

16 h 

2 h 

3 h 

1 h 

40 min 

20 min 

30 min 

30 min 

Total 24 h 

Figure 1. Example of estimate of time spent in microenvironments. 
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Demographic group: Children, age 2 to 4.99 years 

Day and season: Cool weekday 

Activity Time 

Sleeping - home 

Personal - home 

Eating - home 

Indoor playing - home 

Traveling 

At school - indoors 

At school - outdoors 

Other indoor activities - 30 min 

shopping with mother 

Outdoor playing - home 3 h : 

11 h 

1 h 

1 h 

2 h 

11 h 

1 h 

30 min 

30 min 

40 min 

30 min 

20 min 

Total 24 h 

Figure 2. Example of breakdown of time spent in microenvironments 

according to activity. 
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SECTION-3 

RESULTS 

A summary of the time allocations of children exposed to lead is presented in Table 2, which shows the amount of time that each demographic group 

spends in the microenvironments on cool and hot weekdays, Saturdays, and Sundays, along with the appropriate references. In addition to using documented 

facts, PEI made many assumptions to estimate the microenvironmental time 

allocations of the different demographic groups. With the exception of 5 to 

6.99 years old, most children spend more time indoors when it is hot than 

when it is cool. The kindergarten and school-age children spend more time 

outdoors on summer weekdays than when they are in school. Children one year 

of age and older are assumed to spend more time in motor vehicles on Sundays 

than do babies because the older children attend church, visit relatives, or 

eat Sunday lunch in restaurants. The activity patterns of babies and toddlers 

are assumed to be similar to those of their mothers or sitters. Preschoolers 

usually are enrolled in nursery school year-round for an average of 3 h and 

20 min on weekdays. Kindergarten and school-age children attend school for 

5 h and 20 min on cool weekdays and are inside or outside their homes on hot 

weekdays. Preschool, kindergarten, and school-age children are assumed to 

commute for 10 minutes one way to and from school. 

The amount of time children spend in the three microenvironments is 

dependent on the children's ages, the climatic season, the geographical location and family characteristics. The microenvironmental time allocations 

that PEI has estimated represent an average child living in the suburbs. 

Rural children older than one year probably spend more time outdoors and 

commute in motor vehicles for longer times than PEI's estimate indicates. 

On the other hand, urban children probably spend less time outdoors than shown 

in the estimate. Extremely cold climates, hot climates, or rainy areas cause 

children to be indoors more than the estimates in Table 2 indicate. The lifestyles of individual families also would alter these estimates. An affluent 

family would probably travel more, and a low-income family would probably 
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travel less and rarely outside of their own neighborhood. A physically active 

family would spend their leisure time outdoors more than would a physically 

inactive family. 

TABLE 2. SU 

Demographic 

group 

0 to 0.99 yrb 

1 to 1.99 yrb 

2 to 4.99 yrc 

5 to 6.99 yrd 

Day of 

weeka 

WD 

WD 

Sat 

Sat 

Sun 

Sun 

WD 

WD 

Sat 

Sat 

Sun 

Sun 

WD 

WD 

Sat 

Sat 

Sun 

Sun 

WD 

WD 

Sat 

Sat 

Sun 

Sun 

WAR Y OF ACTIVITY 

Season 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

PATTERNS 

Time spen 

Indoors 

22 h 

23 h 

22 h 

23 h 

23 h 

23 h 

21 h 

22 h 

20 h 

21 h 

21 h 

22 h 

19 h 

20 h 

19 h 

21 h 

20 h 

21 h 

20 h 

18 h 

20 h 

20 h 

20 h 

21 h 

'40 min 

20 min 

20 min 

50 min 

20 min 

40 min 

50 min 

40 min 

40 min 

30 min 

20 min 

50 min 

10 min 

10 min 

10 min 

50 min 

50 min 

50 min 

10 min 

10 min 

DF CHILDREN 

t in microenvironments 

Outdoors 

l-h 

40 min 

1 h 20 min 

40 min 

40 min 

20 min 

1 h 50 min. 

1 h 20 min 

3 h 

1 h 50 min 

1 h 30 min 

30 min 

4 h 

3 h .. . 

3 h 50 min 

2 h 30 min 

3 h 

2 h 

2 h 10 min 

4 h 50 min 

3 h 40 min 

2 h 50 min 

3 h 

2 h 

Motor 

vehicles 

20 min 

20 min 

20 min 

20 min 

20 min 

20 min 

20 min 

20 min 

20 min 

20 min 

50 min 

50 min 

30 min 

40 min 

20 min 

20 min 

50 min 

50 min 

1 h 

20 min 

20 min 

20 min 

50 min 

50 min 

WD

 a weekday, Sat = Saturday, Sun = Sunday. 

Reference 2. 

'References 3 through 6. 

References 3, 4, and 6. 
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SECTION 4 

COMPARISON OF THE ESTIMATES OF PEI AND EPA 

For comparison of PEI's estimates with the values presented in the Office 

of Air Quality Planning and Standards (OAQPS) draft staff paper on lead, PEI 

has averaged the elapsed daily time that demographic groups spend in the three 

microenvironments during cool and hot seasons. This average is obtained by 

the equation 

Average daily time in microenvironment 

= (5 WD time + Sat time + Sun time)/7 

where WD equals a weekday. Table 3 presents the average daily time for each 

demographic group in the three microenvironments. This table also shows seasonal variations in the amount of time children spend indoors and outdoors. 

Children 0 to 4.99 years of age are outdoors more in cool seasons than in hot 

seasons, whereas kindergarten and school-age children are outdoors more in 

the warmer months. As children grow older, the overall time they spend outdoors increases. As indicated in Table 3, the average daily outdoor time of 

the four demographic groups of children varies from 40 min (0.62 h) to 4 h 

10 min (4.14 h) in both cool and hot seasons. During cool seasons, the average 

time children spend outdoors ranges from 1 h to 3 h 50 min (3.83 h) ; and during hot seasons, the average time spent outdoors ranges from 40 min (0.62 h) 

to 4 h 10 min (4.14 h). 

In an OAQPS draft staff.paper on lead, EPA estimated that 2 year old 

children spend on the average 2 to 4 h daily outdoors. The EPA estimates 

cover only the amount of time children are indoors and outdoors; they do not 

account for the time children spend in motor vehicles. Nor do the EPA estimates of outdoor daily time show any variation according to season. A more 

complete analysis of the available data could be made if EPA were to include 

estimated ranges of outdoor time that each of the four demographic groups of 

children in Table 1 spend outdoors during cool months, hot months, and the 

entire year in addition to the annual estimated range for children that is 

presented in the draft staff paper. 

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TABLE 

Demographic 

group 

0 to 0.99 yr 

1 to 1.99 yr 

2 to 4.99 yr 

^ 5 to 6.99 yr 

3. AVERAGE DAILY TIME CHILDREN SPEND INDOORS, OUTDOORS, AND IN MOTOR VEHICLES 

Season 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Cool 

Hot 

Time spent 1n microenvironments3 

Indoors 

22 h 40 min (22.67 h) 

23 h 

21 h 40 min (21.64 h) 

22 h 20 min (22.30 h) 

19 h 40 min (19.64 h) 

20 h 30 min (20.57 h) 

20 h 40 min (20.62 h) 

19 h 30 min (19.45 h) 

Outdoors 

1 h 

40 min (0.62 h) 

2 h (1.95 h) 

1 h 20 min (1.28 h) 

3 h 50 min (3.83 h) 

2 h 50 min (2.79 h) 

2 h 30 min (2.50 h) 

4 h 10 min (4.14 h) 

In motor vehicles 

20 min (0.33 h) 

20 min (0.33 h) 

20 min (0.40 h) 

20 min (0.40 h) 

30 min (0.52 h) 

40 min (0.64 h) 

50 min (0.88 h) 

20 m1n (0.40 h) 

Rounding errors in times expressed 1n 10 minute intervals (h, min) are due to conversion from average hours 

to hours and minutes. 
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REFERENCES 

1. Hart, R. Children's Experience of Place. Irving Publishers, Inc., 

New York. 

2. Huffman, W., F. Steinhauser, and E. Pohl. Dose Calculations for the 

Respiratory Tract from Inhaled Natural Radioactive Nuclides as a 

Function of Age I. Compartmental Deposition, Retention, and 

Resulting Dose. Health Physics, 37:517532, 1979. 

3. Rubinstein, E. A., G. A. Comstock, and J. P. Murray (eds.). Television and Social Behavior, Volume IV. National Institute of Mental 

Health, U.S. Department of Health, Education, and Welfare, Rockville, 

Maryland, 1972. 

4. Suter, L. E. Travel to School: October, 1978. U.S. Bureau of 

Census, Series P20, No. 392, 1979. 

5. Moschandreas, D. J., J. Zabransky, and D. J. Pelton. Comparison of 

Indoor and Outdoor Air Quality. Geomet Report No. EA1733. Prepared 

for Electric Power Research Institute, Palo Alto, California, 1981.. 

6. Koontz, M. D., and J. P. Robinson. Population Activity Patterns St. 

Louis Study. Environmental Monitoring and Assessment, 2:197212, 1982. 

7. U.S. Environmental Protection Agency. Review of the National Ambient 

Air Quality Standards for Lead: Assessment of Scientific and 

Technical Information, OAQPS Draft Staff Paper. Office of Air Quality 

Planning and Standards, Research Triangle Park, North Carolina. April 

1985. 

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